The agriculture industry in the United States is very important to the global and American economy. Experts have put the value of agricultural exports at about $140 billion. Across the nation, there are at least 2,060,000 farms. Getting the right equipment is an important factor in the success or failure of farms around the planet. Two questions that are often asked are “What is the difference between 3 phase and single phase motor?” and “Who can use a single phase motor?” Fortunately, Groschop has put together a good overview of how single phase motors work.
According to Groschop, in order to really understand who can use a single phase motor, it is crucial to have a good understanding of the workings of the three-phase motor. In a three-phase motor, a magnetic field that rotates is created by the current that is created by stationary coils. During every phase of the power supply, this magnetic field will rotate about 120 degrees. This rotation creates a current in the rotor bars. In turn, a current is created which also is the source of another magnetic field. Because of the way this all works, these motors are able to start on their own.
In a lot of ways, the manner in which a single phase motor operates is very much the same as the three-phase motor. The main difference is that the number of phases is reduced from three to one. In these instances, there is a magnetic field that oscillates from one position to another. By going to and fro rather than rotating, only one phase is needed. There is no torque at the start of the motor’s phase. That changes as the motor starts up and beings to oscillate from one position to the other. The result is a magnetic field located in the stator.
While these motors are called “single phase motors,” there actually is a second phase. A phase called the “start phase” or “auxiliary phase” is needed in order to get the motor started. Engineers are always working on other ways to get the process started in single phase motors.
There are a few kinds of single phase motors. Four of these are the split phase motor, the shaded pole motor, the two value capacitor motor, and the permanent split capacitor motor or the single value capacitor motor. The main reason these are different is the way the auxiliary or start phase is created. There is no need to use a capacitor for the shaded pole motors and split phase motors. Both the permanent split capacitor and the two value capacitor motors rely on them to make the second of auxiliary phases started. A centrifugal switch is used in the two value capacitor motors and the split phase motors. This shuts down the start or auxiliary phases once the main phase has gotten up and running. Neither the shaded pole motors nor the permanent split capacitor motors have such a switch.
There are tradeoffs, pros, and cons to each of these single phase motors. While the shaded pole motors are inexpensive and simple motors, they do not have a great efficiency rating. When it comes to who can use a single phase motor, these are most often used for applications that do not require a lot of power. The split phase motors are also less expensive but they also have a torque at the start of the process that is low, while they require a higher current early on. By contrast, permanent split capacitor motors are more efficient and start out with a higher torque.
When you are looking at motors for farm work, there are a lot of options. There are good reasons to ask, “Who can use a single phase motor?” Depending on your power needs and the rest, you may be well served by switching from a three-phase motor to a single phase motor. The good news is there are good reasons to make the switch for your motor needs.